Anders Hultman wrote: > > Keith Whaley: > > >Very simply stated,
[...] > >Simple, huh? <g> > > Kinda simple... I've long known that 50mm is considered "normal" or > "standard" but not really why that was so. It's because it matches > the film size, then? Closely matches, anyhow. The best fit is, of course, 43mm. > And the "power figure" is a multiplication > factor compared to this "standard" lens. Yes. > But doesn't the magnification depend on the subject distance? > anders > ------------------------- > http://anders.hultman.nu/ The technical explanation or answer to that specific question goes beyond my capability to explain. I will say that whatever your subject size is, as recorded on the film using a 43mm lens, if you take the very same photo (distance of camera to subject remaining the same) with an 86mm lens, the image size on the film would be doubled, effectively providing a 2X magnification effect. As you maay have noticed, those odd lens sizes are rarely provided for in the real world, but you do have 50mm and 100mm lenses, etc., making it a little easier on multiplication calculations. > Ok, but why then 50mm and not 43mm? My parents sometimes say when we > talk about cameras that "in their times" 45mm was considered normal. True. The historical reason behind why 35mm film "normal" lens has become 50mm instead of staying at 43mm (or 45mm) is out there somewhere, but I can't retrieve it from my crowded gray cells! Someone here will know and help us out! You can still find cameras with 43mm lenses, so the practice is not dead, just not often followed anymore. keith whaley
